Energy Balance, Puberty and Foraging Behavior in Naturalistic Conditions

98-70811 Bronson，F.H.大脑通过评估循环中瘦素的数量来监测身体脂肪。瘦素是一种只在脂肪细胞中表达的基因的蛋白质产物。瘦素被认为是女性青春期的代谢门。这一假说源于相关研究，与一个更古老且颇具争议的假说有关，即青春期排卵只有在能量储备足以支持怀孕和哺乳的情况下才能发生。对这两个假说的担忧是，它们来自于在与瘦素、肥胖和排卵之间的关系实际上进化的条件相比，在异常良性的条件下进行的实验。这项提议的第一个具体目标是使用暴露在模拟野生动物在自然界中经历的条件下的野生家鼠来测试这两个假设。这里提出的替代假设是(A)年轻女性必须处于正能量平衡状态才能排卵，但能量储备本身是间接重要的，因为它们是能量平衡过程的一个组成部分，因此(B)瘦素不是青春期的代谢门。多个实验室的大量研究表明，循环中的瘦素水平在调节进食行为方面很重要。同样令人担忧的是，这些研究是在过于简单化的条件下进行的，瘦素和进食行为之间的关系比现在认为的要复杂得多。这项建议的第二个具体目的是测试这一假设，即瘦素对觅食行为的影响实际上只是其调节觅食经济学(觅食过程中获得的卡路里与丢失的卡路里)的作用的一个组成部分。这一假设将通过暴露在野外复杂觅食条件下的野屋进行验证。总体而言，这项建议的目的是为了极大地阐明能量平衡、觅食行为、瘦素和青春期之间的关系。

98-70811 BRONSON, F.H. The brain monitors body fatness by assessing the amount of leptin in circulation. Leptin is the protein product of a gene that is expressed only in fat cells. It has been hypothesized that leptin acts as a metabolic gate for puberty in females. That hypothesis stems from correlative studies and relates to an older and quite controversial hypothesis, namely that the pubertal ovulation cannot occur until energy stores are adequate to support pregnancy and lactation. A worry about both of these hypotheses is that they stem from experiments done in conditions that are exceptionally benign compared to those in which the relationship between leptin, fatness and ovulation actually evolved. The first specific aim of this proposal is to test these two hypotheses using wild house mice that are exposed to conditions that mimic those that wild animals experience in nature. The alternative hypotheses being offered here are (a) that a young female must be in positive energy balance in order to ovulate but that energy reserves per se are important only indirectly in that they are a component of the energy balancing process and thus (b) that leptin does not act as a metabolic gate for puberty. Numerous studies in a variety of laboratories have shown that circulating levels of leptin are important in regulating feeding behavior. The worry here again is that these studies have been done in oversimplified conditions and that the relationship between leptin and feeding behavior is much more complex that now thought. The second specific aim of this proposal is to test the hypothesis that the the effect of leptin on feeding behavior is actually only one component of its role in regulating the economics of foraging (calories gained vs. calories lost while foraging) This hypothesis will be tested using wild house that are exposed to the kinds of complex foraging conditions they would experience in the wild. Overall, the object of this proposal is to greatly clarify the relationship between energy balance, foraging behavior, leptin and puberty.